New CPUs, faster Wi-Fi, same flaws: Apple’s 2013 iMac reviewed

Apple delivers improvements, but not the ones the iMac needs most.

The GPU

The graphics processors in most of the iMacs are Nvidia GeForce 700M-series chips like the ones you'd find in laptops. These parts share the same underlying GPU architecture as last year's 600M-series chips, but as we've discussed here, they boost clock speeds enough that they'll generally give you 15-25 percent better performance than comparable last-generation chips.

This isn't true of the low-end iMac that we're reviewing, which is actually a bit more interesting than its more powerful cousins: it uses Intel's integrated Iris Pro 5200 GPU, which makes it the first iMac to use integrated graphics since the low-end 2009 iMac and the first iMac ever to use one of Intel's integrated graphics.

If you read "Intel integrated graphics" and then blacked out from a rage-stroke, stop flipping that table and listen: not all of Intel's GPUs are created equal any more. The Iris Pro 5200 shares its underlying architecture with the HD 5000 that you'd find in a computer like the MacBook Air, but it comes with 128MB of eDRAM integrated into the CPU package that alleviates the memory bandwidth problems that have historically constrained integrated GPUs.

The eDRAM essentially serves as a large cache for both the CPU and GPU—while the GPU still uses the main system memory when it needs to, the cache makes those performance-sucking trips from the GPU to the system memory and back again less frequent. Microsoft and AMD have taken a similar route with the Xbox One, integrating 32MB of eDRAM into the console to help compensate for its slower (but cheaper) DDR3 memory.

The point is, the Iris Pro 5200 is technically an integrated GPU, but it nevertheless offers performance slightly above the dedicated GeForce GT 640M in last year's low-end iMac under both OS X and Windows 8. We've also provided numbers for the 2011 iMac from last year's review for context, as well as the Intel HD 5000 GPU in the 2013 MacBook Air to show how the Iris stacks up against a more "traditional" integrated GPU.

In the Cinebench test running in OS X, the Iris Pro 5200 does much better than the GPUs in its predecessors.

Switching to Windows 8, the Bioshock Infinite benchmark shows that, on average, the Iris Pro 5200 can be as much as twice as fast as the HD 5000. The increased CPU power may also be contributing to this increase, however.

We keep the HD 5000 in the mix and add last year's scores from the 2012 iMac. In Portal 2, performance stays just about level between generations. The HD 5000 is much slower.

Arkham City (which, like Bioshock Infinite, runs the popular Unreal Engine 3) shows us another game where Intel edges out Nvidia.

Like Cinebench under OS X, 3DMark 11 in Windows shows the 2013 iMac outshining its forebears.

Intel's biggest and baddest integrated GPU is usually just barely faster than a midrange dedicated GPU from last year, but that's actually kind of a big deal for Intel. Five years ago Apple was ejecting Intel's integrated graphics from its laptops in favor of better-performing integrated graphics from Nvidia; now the features and performance of Intel's integrated GPUs are good enough that it's starting to replace Nvidia's dedicated chips in desktops. Intel's HD 4000 and 5000 series GPUs (as well as AMD's more recent APUs) have all but eliminated the market for low-end dedicated graphics cards in laptops especially, and while the Iris Pro 5200 has been relatively rare so far, it shows that integrated graphics are only going to continue encroaching on the highest-volume segments of the graphics market.

The Iris Pro 5200's performance also has interesting implications for Apple's Retina MacBook Pros, which are due for a refresh any day now. This integrated GPU's performance is good enough that, in the 15-inch model at least, Apple could potentially get away with marketing the new laptop as having roughly the same graphics performance with much better battery life (both because the Iris would consume less power than the GeForce GT 650M, and because it would free up space on the inside of the laptop that could be used for a larger battery). The graphics performance might actually drop slightly, but the Iris is still enough to drive that Retina display and the benefits might outweigh the downsides from Apple's perspective—something similar happened in the transition between the 2010 and 2011 MacBook Airs, where Apple gave up a little bit of graphics performance in order to give the Airs a huge boost in CPU performance.

At any rate, the lesson for iMac buyers is that despite the move from Nvidia to Intel, the low-end iMac will still give you good 3D performance relative to last year's.

The SSD (and, sigh, the HDD)

We'll begin with the good news first: for iMacs that come with Fusion Drives and with SSDs, Apple has switched from using a SATA storage interface to using a faster PCI Express interface. Apple already made this jump in the 2013 MacBook Air, and since the company tends to use the same components in all of its products when it can, the performance of SSD-equipped iMacs should be about the same. The standard mechanical HDDs in the iMacs still use a SATA interface—our base model has a SATA II drive attached to a SATA III interface.

The bad news is that all four base iMac configurations, which start at $1,299 and run all the way up to $1,999, ship with standard mechanical hard drives by default. The 21.5-inch models come with 5400RPM drives, while the 27-inch models use slightly faster 7200RPM drives. Prices for solid-state upgrades have come down a bit even if they're still well above market prices (adding a 128GB SSD to the 1TB HDD to make a 1TB Fusion Drive only costs $200 now instead of $250 as before, and a new 1TB SSD option has been added at the high end for a whopping $1,000), but none of these iMacs include solid-state by default, and base models are all that you can walk out of an Apple Store with unless you order through the online store first.

Especially in the 21.5-inch iMac, this decision has a much larger impact on general system performance than the slight CPU and GPU upgrades. You can feel it in everything from boot time to app launch time to file copy time—that spinning hard drive is definitely the performance bottleneck here, just as it was last year. We'll use boot time and the QuickBench performance test to compare the iMac and a 2013 MacBook Air with a PCI Express SSD just to give you some idea of the performance gap we're looking at.

That nice, quad-core iMac is going to be faster for CPU-intensive tasks like video exporting and heavy multitasking, but the MacBook Air almost always manages to feel snappier by virtue of having an SSD.

Why Apple can ship a $999 laptop with 128GB of solid-state storage but can't do the same for a $1,999 desktop is puzzling. Since the introduction of the 2010 MacBook Airs the company has been a big booster of solid-state storage, and yet none of its flagship desktops include it as a default option. It's possible that Apple thinks a large drive is more appropriate for a big, stationary desktop than a small SSD would be, but Fusion Drive is a technology purpose-built to offer customers SSD-class performance with HDD-like capacity. The iMac on my desk has a 1TB Fusion Drive in it that's worked flawlessly for almost a year now, and it rarely feels any slower than my SSD-equipped Air.

It goes without saying that you shouldn't buy any iMac without a Fusion Drive configured, at least. Those upgrades start at $200 for all computers, which raises the base price by a not insignificant amount, but the performance benefits are more than worth it.

1.3Gbps of 802.11ac goodness

The 2013 iMac is Apple's second product to get the bump to 802.11ac after the 2013 MacBook Air, but we aren't quite looking at the same configuration here. The MacBook Air uses a two-stream (2x2:2) antenna configuration—since a single two-way 802.11ac stream can net you speeds of up to 433Mbps, the MacBook Air can connect to 802.11ac routers at speeds of up to 867Mbps. The iMac uses a three-stream (3x3:3) configuration, adding another antenna for a theoretical maximum transfer speed of 1.3Gbps (the Haswell MacBook Pros, when they're released, should use this same configuration). This is even higher than is possible with wired gigabit Ethernet, though the normal interference and overhead associated with wireless networking means that a wired connection is going to remain the faster and more stable option the majority of the time.

The worst of OS X's 802.11ac issues were resolved in the 10.8.5 update earlier this month, so buyers with capable routers should get a nice wireless speed bump over the 802.11n iMacs of years past.

We ran two performance tests connected to our AirPort Extreme Base Station, which is capable of 1.3Gbps connections. The first is iPerf, a network testing which measures raw performance without the overhead associated with a file transfer protocol like AFP or SMB. The second is an AFP file transfer test, in which we transfer one 6GB file using the AFP protocol to give you an idea of best-case file transfer performance. For all tests, the computers are positioned about ten feet away from an 802.11ac AirPort Extreme Base Station with nothing obstructing the signal between the two. In all tests, the computers are connecting to a Mac mini server connected to the AirPort via gigabit Ethernet.

Surprisingly, while the 2013 iMac handily beats the 802.11n adapter in our 2012 iMac, it doesn't really exceed the MacBook Air's performance by much despite the presence of the extra antenna. It could be the case that OS X is still having some 802.11ac-related networking issues, but this seems unlikely—even when the file transfer speeds were being held back, iPerf still performed normally.

As it turns out, the third antenna in the 2013 iMac is less useful for its maximum possible performance and more for its range. We moved both the Air and the new iMac about thirty feet from the router and put a wall in between them and ran iPerf again.

Here, the iMac's 802.11ac adapter nearly doubles the performance of the Air's. The third antenna is at least a part of the reason, but we'd also bet that the iMac has more room inside it for a larger, stronger antenna than the Air does.

Seriously, spring for the SSD

The iMac isn't a system that you upgrade every year, and its refresh cycle reflects that fact. Every three-or-so years we get a big exterior overhaul, and the rest of the time Apple is content to keep the insides modern without making a big fuss about it. If you liked the 2012 iMac, this year's version is a better take on the same idea. If you hated the 2012 iMac (or certain things about the 2012 iMac, like its reduced upgradeability), Apple has done nothing to assuage your concerns.

Particularly perplexing is the lack of a standard SSD option in an age where most of Apple's laptops include them by default. You can get cheaper and larger SSDs than you could last year and Fusion Drive has proven itself to be a good, reliable way to mix SSD performance with HDD capacity, but even if you're buying the top-end iMac you still have to pay an extra $200 to eliminate the performance bottleneck that the mechanical hard drive has become. Solid-state storage is cheaper than it's ever been, and if there's one upgrade we're hoping for in the 2014 iMacs, that's the one.

The good

Still a nice-looking, well-built computer

Fast quad-core processors and nice IPS panels across the line

Increased graphics performance, even in the Intel-equipped model

802.11ac is a nice addition if you've got a compatible router

Fan noise, heat, and screen reflectivity are all down from pre-2012 models

The bad

21.5-inch model doesn't offer user-accessible RAM slots

No huge performance leaps from last year, which is perhaps to be expected given the maturity of the desktop market

The ugly

SSDs and Fusion Drives are still add-ons rather than standard options, making these iMacs feel slower than they have any right to feel unless you pay for the upgrade

Andrew Cunningham / Andrew has a B.A. in Classics from Kenyon College and has over five years of experience in IT. His work has appeared on Charge Shot!!! and AnandTech, and he records a weekly book podcast called Overdue.